UK Chancellor George Osborne will officially unveil the new £1 coin in today's budget announcement.
The new 12-sided coin is based on the old threepenny bit and will replace the current coin, which has been in circulation for 30 years. The new £1 coin will be introduced in 2017.
Osborne will reveal in his Budget 2014 speech that a replacement is needed because the pound coin has become vulnerable to sophisticated counterfeiters.
Royal Mint now estimates that about 45 million of £1 coins in circulation are forgeries.
"After 30 years loyal service, the time is right to retire the current £1 coin, and replace it with the most secure coin in the world," Osborne will say.
"With advances in technology making high value coins like the £1 ever more vulnerable to counterfeiters, it's vital that we keep several paces ahead of the criminals to maintain the integrity of our currency.
"We are particularly pleased that the coin will take a giant leap into the future, using cutting edge British technology while at the same time paying a fitting tribute to past in the 12-sided design of the iconic threepenny bit."
The Treasury will also confirm that while the Queen will remain on one side, the other side's design will be open to public competition.
"The Bank welcomes [the] news from the Treasury as another step forward in our collective efforts to maintain public confidence in the currency. Coins are the responsibility of the Royal Mint and together with the Bank's decision to produce polymer banknotes, this change will enhance the security and integrity of the currency," said the Bank of England in a press statement.